US forces were ready to strike inside Syria last year but the military mission ultimately was scuttled, says a senior GOP senator.

Sen. Bob Corker, R-Tenn., the incoming Foreign Relations Committee chairman, said Wednesday that a “10-hour operation” was scheduled in Syria last year. His comments came during an appearance at a conference here sponsored by the Foreign Policy Initiative.

Corker said senior American officials opted against green-lighting the operation, a decision Corker dubbed “the worst” foreign policy development in the last five years.

He later told reporters the “10-hour” duration in his description of the operation was merely his own time frame, meant to illustrate it was to be a limited mission.

There were no plans to insert US ground forces, Corker said, only to conduct airstrikes.

“An operation that was going to be very targeted, very brief,” Corker told reporters. “I think it’s safe to say during that period of time there were no ground forces ever contemplated.”

He said Obama took a highly publicized “Friday evening walk” and then “the White House decided it was going to go to Congress” and seek authorization before launching air strikes.

In late summer 2013, Obama seemed poised to strike parts of Syrian President Bashir al-Assad’s chemical weapons program after saying the use of those arms constituted a “red line.”